Word processing systems have evolved from relatively simple text processors which facilitated the manipulation of character strings to the sophisticated multitasking processors of today which are capable of such diverse applications as communications, calculations and data processing emulations. It is not uncommon, for example, to provide a word processing system with a calculation application to include the generation of graphics data based on calculated or input numerical data. This is because it is often easier to interpret the numerical data when it is presented as a bar, pie or line graph, for example.
The problem arises, however, in the presentation of the graphics data. Generally, the visual display of graphics data on a CRT display has been accomplished with an APA display. Word processing systems typically use a character box or non-APA display. The advantage of the character box display is that it requires much less memory than an APA display of even moderate resolution. The disadvantage is so far as the presentation of graphics data is concerned is the inability of the character box display to support the display of characters not defined by the character box.
The above referenced application Ser. No. 06/493,677 entitled "Internal Image and Bit Array for Display and Printing of Graphics" discloses an apparatus which provides a word processing system using a non-APA display and a letter quality printer, both character box devices, with the ability to both display and print graphics data. The invention described in that application provides an internal image and bit array apparatus to contain the data structures necessary and sufficient to both display and print the graphics data. These data structures are (1) output by the process that converts numeric data values into image data and (2) input to the display process and the print process. These are the central mechanisms that make graphics on a character box device possible. However, in order for these mechanisms to produce a display of graphics data, it is necessary to map the high resolution graphics data in the bit array into the internal image and then to use as few characters as possible selected from a limited character set in read only storage (ROS) in order to display curved lines.